The present invention relates to a field-sequential color image display apparatus and method with improved picture quality.
Field-sequential color is used in, for example, projection television systems, data projectors, head-mounted displays, monitors, and viewfinders, where it enables high-resolution color images to be displayed with comparatively few monochromatic picture elements. In conventional field-sequential color image display apparatus, red, green, and blue monochromatic images are displayed in the sequence shown in FIG. 18, in which R1 and R2 are red, G1 and G2 are green, and B1 and B2 are blue. R1, G1, and B1 together constitute one field, if interlaced scanning is used, or one frame, if progressive scanning is used, and R2, G2, and B2 constitute the next field or frame. The image display rate is three times the field rate or frame rate. The eye perceives the separate red, green, and blue images as a combined full-color image. In known field-sequential color image display apparatus, the monochromatic images are generated as gray-scale images and are colorized by means of, for example, a rotating filter wheel, color switches utilizing birefringent materials, or red, green, and blue light sources such as light-emitting diodes that are switched on and off sequentially.
The red, green, and blue monochromatic images are technically referred to as red, green, and blue fields, as implied by the name xe2x80x98field-sequential color,xe2x80x99 but the term xe2x80x98monochromatic imagexe2x80x99 will be used herein instead of xe2x80x98field,xe2x80x99 to avoid confusion with the fields in interlaced scanning.
A problem encountered in conventional field-sequential color image display apparatus is that the individual primary colors (red, green, blue) are perceived separately at the edges of moving objects. This problem, referred to as color breakup, is particularly obvious when the primary colors are combined to produce a black-and-white image. Color breakup also occurs in still images, when the viewer""s eye scans across the display.
An object of the present invention is to reduce color breakup in a field-sequential color image display.
The invented method of displaying a color image comprises the steps of:
receiving image data for the red, green, and blue components of one full-color image;
decomposing the image data to generate more than three monochromatic images, including at least one red monochromatic image, at least one green monochromatic image, and at least one blue monochromatic image; and
displaying the monochromatic images sequentially.
In one aspect of the invention, the monochromatic images include N red monochromatic images, N green monochromatic images, and N blue monochromatic images, where N is an integer greater than one. Each monochromatic image is displayed following a monochromatic image of a different color.
In another aspect of the invention, the monochromatic images include one white monochromatic image, as well as at least one red, one green, and one blue monochromatic image. The terms xe2x80x98white monochromatic imagexe2x80x99 and xe2x80x98white imagexe2x80x99 are used herein to mean an image including white, black, and shades of gray.
Both aspects of the invention reduce color breakup by shortening the intervals at which monochromatic images of different colors are displayed. In the second aspect of the invention, the white monochromatic image is completely free of color breakup.